Short circuits in internal cells can cause batteries, in particular Li-Ion batteries, to experience thermal runaway which can cause the batteries to no longer function. Typically, anode and cathode portions of a cell are separated by an insulative barrier. However, this barrier can deteriorate such that current can flow between the cathode and anode portions through the barrier. This internal short circuit reduces the internal resistance of the battery and can lead to thermal runaway. For example, when a short circuit reduces the internal resistance, the likelihood of overcharging or over-discharging the cell increases. Overcharging or over-discharging the cell increases the cell temperature and can eventually lead to thermal runaway.
Moreover, as the temperature of the battery rises, the barrier can deteriorate further which increases the internal short circuit and decreases the internal resistance of the battery. This problem can be exasperated by manufacturing defects in the cell where metal debris from the fabrication process can reduce the effectiveness of the internal barrier thereby leading to a short circuit. Detecting and managing internal short circuits can extend the life of the cell (i.e., prevent or slowdown the rate at which the short circuit increases) and prevent thermal runaway.